Neptune, 59, spent more than two years in prison after his arrest on charges of orchestrating the killing of opponents of ousted President Jean-Bertrand Aristide at the start of a rebellion that engulfed the country.

The former prime minister has denied the allegations and reportedly refused meals for weeks to protest his detention.

Dyotte said he could not comment on the status of the charges against Neptune, who was prime minister from 2002-2004 under Aristide.

Mario Joseph, an attorney for Neptune, said the former prime minister had been released for humanitarian reasons because of his health, which had deteriorated in recent months. He predicted that the case against Neptune would soon be dismissed entirely.

"After the hospital, he is free to go home," Joseph said. "I'm confident that charges will be dropped."

The lawyer said he did not know Neptune's precise medical condition, but said it is related to his repeated hunger strikes while in custody.

"He is very weak," Joseph said.

The U.N. mission in Haiti welcomed Neptune's release. It said in a statement Thursday that it had been concerned about the "prolonged detention" of the country's former leader.

Neptune will remain under the care of U.N. medical staff until he is well enough to return to his family, the statement said.

A U.S.-backed interim government, which was replaced on May 14 by President Rene Preval, had faced mounting international pressure to release Neptune, whose case was emblematic of the country's dysfunctional judicial system that has left hundreds of people jailed for long periods without trial.

Last year, U.S. Secretary of State Condoleezza Rice cited Neptune's case as an example of the need to improve Haiti's justice system, which is burdened by corrupt judges and police and overcrowded prisons.

Neptune was accused of orchestrating the killings of at least 25 government opponents in the western town of St. Marc on Feb. 9-11, 2004, some two weeks before Aristide was ousted following a three week armed rebellion.

After his arrest in June 2004, Neptune became a rallying point for militants demanding the release of hundreds of jailed Aristide officials and loyalists.

In the hours after Neptune's release, local media reported gunfire across Port-au-Prince, the Caribbean nation's volatile capital. Most of the lawlessness was reported in Martissant, a slum of tin-roof shacks in the city's southwest where warring street gangs were blamed for a massacre of 22 people earlier this month.

Newspapers reported that a nearby church and soccer stadium were filled with people trying to escape the violence in the troubled neighborhood, an Aristide stronghold.